阅读理解。
A grown-up person has ten or eleven pints(品脱) of blood inside his or
her body. We can lose a pint of blood without feeling anything, but if we lose too much blood, we feel weak and cold. Our faces become pale (苍白). We may die. This is what often happens when somebody is hurt in an accident, or a soldier is hurt in a war. Many people used to die in this way. But today they can be taken to hospital and given more blood. Almost at once they feel
better. Their faces are no longer pale. They do not die.
Where does this blood come from? People who are healthy may donate
blood to a bloocl bank so that it can be used to save people's lives. When they go to donate blood, a special kind of needle(针) is put into the arm. It does
not hurt. The blood runs through the needle and through a rubber tube(橡胶管) into a bottle or a bag. A pint of blood is taken this way. The person who
has given blood drinks a cup of tea or coffee and rests for a few miuntes. Then he feels quite well. And he may give his blood this way six months later.
A person who gives blood feels happy, because he knows that his blood
will be used to save someone's life. Perhaps one day he himself will need
blood.
When you are older, you may give blood, too. But you cannot do this until you are eighteen.
1. There are____________ pints of blood in a grown-up body.
A. three
B. a lot of
C. more than eleven
D. ten to eleven
2. A person who loses a lot of blood may die. But if he is given some blood, he _______ .
A. may die
B. may feel better slowly
C. feels weak and ill
D. feels better very quickly
3. A person who has given blood can give blood again after___________________
A. a few minutes
B. six months
C. drinking a cup of tea or coffee
D. eighteen months
4. A person cannot give blood if' he is .
A. lealthy
B. unhappy
C. under eighteen
D. too fat
5. Which of the followings is TRUE?
A. People who are not healthy enough can't donate I)lood.
B. The person who has given blood mustn't drink tea.
C. If a person loses a pint of blood, he'll feel weak and cold.
D. People give blood so that they can be healthier.
:
:1
得
，
，故B错误；又由v=gt得，
，故A正确；b与a开始下落的时间差
小于c与b开始下落的时间差
，故C正确；小球下落的加速度均为g,与重力及质量无关，故D错误。